Nasturtium in Zone 7A — Southeast

Nasturtiums are a fantastic addition to any Southeast garden. Their peppery leaves and vibrant flowers add a unique flavor to salads, plus they're beautiful and attract pollinators. You'll enjoy their versatility in the kitchen and the satisfaction of growing something so easy and rewarding.

Our long summer growing season makes nasturtiums a breeze, even with the challenges of humidity and clay soil. With a 225-day growing season, you have plenty of time to get a few rounds of planting in. Proper timing and a little attention will have you enjoying these beauties from late spring through fall.

While nasturtiums prefer direct sowing, you *can* start them indoors if you're eager to get a head start. Sow seeds indoors from late February through mid March, about four weeks before you plan to transplant them outside. Use seed trays with a good seed-starting mix and keep them in a warm location with plenty of light – a sunny windowsill or under grow lights will work.

Bottom watering is a great way to keep the soil moist without overdoing it. Just set the tray in a shallow dish of water and let the soil absorb what it needs. Our moderate spring weather means you don't *need* to start them indoors, but if you want an earlier bloom, it's an option.

Transplant your nasturtium seedlings outdoors from early to late April, after the last expected frost. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind.

When transplanting, space the plants 10-12 inches apart. Keep an eye on the weather forecast; those late-season cold snaps can still happen, so be ready to cover your seedlings if needed.

Direct sowing is the preferred method for nasturtiums, as they don't always love being transplanted. Sow seeds directly into the garden from early April through late August. This gives you a long window to stagger plantings for a continuous harvest.

Choose a spot with full sun to part shade and prepare the soil by loosening it and removing any weeds. Nasturtiums aren't picky about soil, but good drainage is always a plus, especially with our clay soil. Plant the seeds about ½ inch deep and space them 10-12 inches apart. Keep the soil consistently moist until the seedlings emerge, which usually takes about a week or two, depending on soil temperature.

Nasturtiums are wonderfully drought-tolerant, which makes them ideal for our sometimes unpredictable Southeast weather. They actually thrive in slightly poor, dry soil. Overwatering is a bigger concern than underwatering with these plants.

During the spring and fall, when temperatures are milder, you likely won't need to water them at all unless we're experiencing a prolonged dry spell. In the heat of summer, though, especially during those weeks when the high hits 92°F, give them a good soak once a week if it hasn't rained. Stick your finger about two inches into the soil; if it feels dry, it's time to water. Aim for about an inch of water per week.

Water at the base of the plants rather than overhead, especially in our humid climate, to help prevent fungal diseases. Yellowing leaves can be a sign of overwatering, while wilting leaves indicate they need a drink. A light layer of pine straw mulch can help retain moisture and suppress weeds.

You can expect your first harvest of nasturtium flowers and leaves from late May through early November. Nasturtiums are ready to harvest about 55 days after planting. The flowers are best when fully open, showcasing their vibrant colors. The leaves are most tender when young.

To harvest, simply snip off the flowers or leaves with scissors, being careful not to damage the plant. Regular harvesting encourages more blooms and keeps the plant producing throughout our long summer. As the first frost approaches in early November, harvest any remaining flowers and seed pods. You can even pickle the seed pods for a caper-like treat!

Here are some common problems you might encounter with nasturtiums in the Southeast:

Aphids

• What it looks like: Clusters of small, pear-shaped insects on stems and undersides of leaves. Leaves may be sticky or distorted.
• What causes it: Aphids are attracted to stressed plants and thrive in warm, humid conditions. Our Southeast humidity provides the perfect environment for them.
• How to fix/prevent it: Nasturtiums are sometimes used as a trap crop for aphids, drawing them away from other plants. If the infestation is heavy, try blasting them off with a strong stream of water from your hose. Insecticidal soap can also be effective.

Cabbage Caterpillars

• What it looks like: Holes in leaves, often with green or brown caterpillars present. You might also see dark droppings on the leaves.
• What causes it: These caterpillars are the larvae of cabbage white butterflies, which are common in the Southeast.
• How to fix/prevent it: Handpick the caterpillars off the plants. You can also use a product like BT (Bacillus thuringiensis), which is a natural insecticide that targets caterpillars.

Black Fly

• What it looks like: Small, black flies clustered around new growth. Stunted growth and distorted leaves may also occur.
• What causes it: Black flies, like aphids, are attracted to stressed plants and can quickly multiply in warm, humid conditions.
• How to fix/prevent it: Improve air circulation around the plants. A strong spray of water can dislodge them. Insecticidal soap can also be used.

Southeast Specific Challenges: The hot, humid summers and wet-summer rainfall in the Southeast create an ideal environment for fungal diseases. Ensure good air circulation around your nasturtiums and avoid overhead watering to minimize disease pressure. Japanese beetles can also be a nuisance, munching on leaves and flowers. Handpicking them or using traps can help control their populations.

Nasturtiums make excellent companions for many garden vegetables in the Southeast. Planting them near tomatoes, cucumbers, and squash can help deter pests like squash bugs and aphids. They also do well with broccoli and cabbage, helping to repel cabbage moths.

Avoid planting nasturtiums near fennel, as it can inhibit their growth. Otherwise, they're fairly easygoing and get along well with most other plants in the garden.